Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
2000-04-17
2001-10-16
Jaworski, Francis J. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
Reexamination Certificate
active
06302847
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to ultrasonic imaging and, more particularly, to an ultrasonic scanning apparatus and method that can be used, inter alia, for obtaining images of the brain.
BACKGROUND OF THE INVENTION
The brain is an inaccessible organ that cannot be examined by visual, palpatory or auscultatory methods currently used in clinical medicine. Although the suggestion of brain imaging was made early in the history of ultrasound for medical diagnostics, existing brain imaging techniques are non-ultrasonic in their nature. The most popular brain imaging techniques are Magnetic Resonance Imaging (MRI), and Position Emission Tomography (PET). The equipments providing such imaging are extremely expensive. Furthermore, PET requires chemical radioactive tracers, and MRI works with a strong magnetic field. Both techniques need a long integration time for metabolic activity or structure measurements (e.g. about 45 min. for PET, and 2 min. for MRI), so they are incapable of showing real time live pictures of the human brain.
There are several real time, two-dimensional color ultrasonic scanning techniques currently used in clinical diagnosis. The most popular are Color M-Mode Scanning and Color Doppler. However, they are not applicable for brain imaging, and also suffer some disadvantages.
The image in Color M-mode Scan is interpreted by pattern recognition, but it does not correlate with the usual two dimensional structure anatomy as depicted in real time imaging. The detected motion in the lateral direction is not portrayed because of the limited field of view. Furthermore, this scanning is based on two-dimensional extrapolation of geometric shapes based on one dimensional measurement, which introduces an error. This scanner is mainly used in echocardiology.
The major disadvantages of duplex scanning in Color Doppler are related to the fact that the flow is not evaluated simultaneously throughout the field of view but rather is sampled at a particular location as selected by the sonographer. To establish the region flow pattern, an FFT analysis must be performed at multiple sites throughout the vessel, which requires precise positioning of the sampling volume; color coding is based on the average, rather than the peak Doppler shift; progressing across the field of view, a vessel with constant flow is depicted with different colors and so on. The highest priority for such a scanner is the observation of arterial and venous flow. Furthermore, such techniques are based on a velocity detection, so they are not able to measure small amplitude variations, and cannot provide imaging through the skull.
It is among the objects of the present invention to provide improvement over prior art ultrasonic techniques for imaging the body, and which can be used for practical imaging and diagnosis of the brain.
SUMMARY OF THE INVENTION
The disclosed new type of two-dimensional, real time, color ultrasonic scanner is able to measure and display brain metabolism by monitoring amplitudes of localized changes of intracranial interfaces. A real time image is obtained with a flexible array of transducers which eliminates the strong reflection from the skull due to a shape mismatch, and reduces the topological mislocations in the image. The image is generated by a superposition of a gray scale image representing static structures, and a color coded pattern representing motion information. The pulsations observed in certain parts of the brain are depicted by image subtraction. In this way, only the regions where these pulsations occur can be observed. All other echoes will be canceled during subtraction, since they represent static structures. The motion detection, based on image subtraction, gives the scanner the capability to detect multidirectional motion of the intracranial interfaces, and to display the amplitude of the motion in real time. A digitally controlled time-gain compensation allows imaging of preselected brain areas. Monitoring the image synchronously with the heart beat and an external stimulus presence can give clinicians the opportunity of a real time visualization of detailed cross-sectional anatomy of portions of the human brain, permitting direct observation, mapping the structure and function in a normal human brain, and studying the pathophysiology of brain abnormalities by demonstrating structural, metabolic, and neurochemical abnormalities.
The scanner hereof can also be applied in other areas of medical diagnosis beyond neurology, for example as echocardiology or gynecology. Although the scanner is designed primarily for medical imaging, some of the features hereof can also be applied to sonar, nondestructive testing (NDT) of materials, or precision motion sensing.
In accordance with a form of the invention there is disclosed an apparatus for producing an image of a body, comprising: transmitter means for producing energizing signals; transducer means coupled with the transmitter means for producing ultrasonic energy for transmission into the body and receiving ultrasonic energy reflected from the body; receiver means coupled with the transducer means for producing receiver signals; storage means for storing the receiver signals; difference means responsive to the receiver signals and an output of the storage means for producing motion signals as a function of the difference between the receiver signals and the storage means output; and means for displaying the motion signals.
In a preferred embodiment of this form of the invention, the means for displaying the motion signals comprises means for quantifying the amplitude of motion represented by the motion signals to produce motion amplitude signals, and means for displaying the motion amplitude signals. In this embodiment, the means for displaying the motion amplitude signals comprises means for color coding the motion amplitude signals with different colors for different motion amplitudes, and for displaying the coded colors.
In accordance with a further form of the invention there is provided a transducer array for use in an ultrasonic scanner for imaging a brain in a skull. The transducer array comprises: a flexible substrate that can conform to the shape of the skull; an array of transducers mounted on the substrate; a backing block mounted on the back of each transducer of the array; and means for coupling electric signals to and from each transducer of the array.
In a preferred embodiment of this form of the invention, the substrate is a plastic substrate and the array is a linear array of piezoelectric transducers individually mounted on the substrate. The backing blocks are formed of material having an acoustic impedance matched to that of the transducer material. Also, the substrate has an acoustic impedance that is between the acoustic impedance of the transducers and the acoustic impedance of the skull skin layer.
Further features and advantages of the invention will become more readily apparent from the following detailed description when taken in conjunction with the accompanying drawings.
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Dinev Petko D.
Glenn William E.
Florida Atlantic University
Jaworski Francis J.
Novack Martin
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